Rheometrics Mechanical Spectrometer Research Articles

Dynamically vulcanized CNC‐reinforced thermoplastic elastomer based on PP/EPDM: Morphology and mechanical properties control via interfacial compatibilization

AbstractIn this study, dynamically vulcanized thermoplastic elastomer nanocomposites consisting of polypropylene (PP) as the thermoplastic matrix, ethylene propylene diene monomer (EPDM) rubber as the dispersed phase, and needle‐like cellulose nanocrystals (CNC) were investigated. The two polymers were melt blended in a ratio of 70/30 (PP/EPDM) and 60/40% w/w (PP/EPDM) together with CNC (2, 3, and 5 phr) and sulfur‐curing system. The potential of EPDM‐g‐MA and PP‐g‐MA's as interfacial compatibilizers for enhancing interfacial interactions between components and partitioning of CNC between the two polymer phases was examined by measuring the decrease in the size of EPDM particles. The resulting thermoplastic vulcanizates (TPV) were characterized using a melt rheometric mechanical spectrometer (RMS), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and tensile tests. The inclusion of any type of interfacial compatibilizers led to enhanced tensile properties when compared to the samples lacking compatibilizers in both TPVs and TPEs in different ratios. EPDM‐g‐MA was found to be more effective for 60/40% w/w (PP/EPDM) TPVs, while PP‐g‐MA showed higher potential for 70/30% w/w TPVs. The CNC‐reinforced TPVs displayed higher melt elasticity than their unloaded counterparts. These nanocomposites also showed reduced EPDM particle size, enhanced Young modulus, and a higher degree of crystallinity.Highlights Nanocomposite thermoplastic vulcanizates (TPVs): polypropylene (PP)/ethylene propylene diene monomer (EPDM)/cellulose nanocrystals (CNC) with matrix‐dispersed morphology. Interfacial enhancement: Compared EPDM grafted maleic anhydride (EPDM‐g‐MA) and PP‐g‐MA potentials. Tensile properties: EPDM‐g‐MA is more effective in higher rubber content TPVs. Mechanical enhancements: Improved properties and Young's modulus in CNC‐filled TPVs. Diverse applications: PP/EPDM/CNC nanocomposites in auto, electrical, electronic, and packaging industries.

Fabrication of a packaging film based on PLA blends: The evolution of physical, mechanical, and rheological properties

AbstractToday, the use of biodegradable polymers has become widespread in a wide range of industries. This research scrutinized the physical, mechanical, and rheological properties of poly (lactic acid)/poly (ethylene oxide)/carbon nanotube (PLA/PEO/CNTs) blend nanocomposites, as a good candidate for usage in the packaging industry. PEO and CNTs were added at various concentrations to improve the flexibility, toughness, gas permeability, thermal stability, and mechanical properties of PLA via solution blending. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Field Emission Scanning Electron Microscope (FESEM), water contact angle (WCA), rheometric mechanical spectrometer (RMS) test, gas permeability, and tensile characterization were performed to characterize the properties of the prepared blends and nanocomposites. The experimental results revealed that the addition of 25 wt% PEO to the PLA matrix made a partially miscible blend with a droplet‐matrix morphology. PEO at this concentration increased the elongation at break (from 2.2% to 18%) while reducing the modulus (from 25 to 6 MPa). Also, the experimental results indicated that the miscibility of PLA and PEO was enhanced by the addition of 1 wt% CNTs to the prepared blend, associated with diminished entropy of mixing in the LCST phase diagram. Theoretical calculations predicted that the CNTs would be localized in the PLA phase which increased the total crystallinity of the sample by 28%, considerably reducing the amount of gas permeation into the nanocomposite. In addition, the introduction of the CNTs to the blend increased the elongation at break and tensile strength by 13% compared to pure PLA and lowered the rate of thermal degradation effectively. Also, the final results showed that the COOH‐CNTs located in the PEO phase caused a decline in the crystallinity and an increase in the gas permeability of the prepared nanocomposite.Highlights Improvement of physical properties of PLA by blending with PEO and CNTs. A deep investigation on rheological behavior of the prepared nanocomposite. Increasing the crystallinity degree of PLA/PEO blend by adding CNTs. Improvement of the miscibility between PLA and PEO in the presence of CNTs. Controlling the CNTs localization by surface modification.

A new nanocomposite based on polylactic acid/butadiene rubber/clay: Morphology development and mechanical properties

AbstractIn this work, several samples based on poly(lactic) acid (PLA)/butadiene rubber (BR) blend with and without nanoclay (Cloisite 30B) were prepared using an internal mixer. Various methods were used to characterize the samples, including scanning electron microscopy (SEM), atomic force microscopy (AFM), x‐ray diffraction (XRD), rheometric mechanical spectrometer, stress–strain, and impact strength tests. The SEM results showed the droplet‐matrix morphology for all prepared samples. With the incorporation of nanoclay, the mean diameter of the BR droplets generated within the PLA matrix decreased. AFM test revealed the placement of nanoparticles in the PLA phase, which was consistent with the thermodynamic prediction of their location. The XRD test showed that the interlayer space of nanoclay expanded by 86% due to the diffusion of polymer chains between them. In the rheology test, this resulted in an increment in modulus and viscosity at low frequencies for the nanocomposites compared to the simple blend. The highest elongation at break was observed for the PLA/BR blend containing 10 wt% BR with approximately 40 times its value for the neat PLA, while the impact resistance increased up to three times.

A systematic study on the effect of co-catalysts composition on the performance of Ziegler-Natta catalyst in ethylene/1-butene co-polymerizations

Effect of the type and composition of conventional co-catalysts on the catalytic performance of Ziegler-Natta catalysts has been investigated by means of a combined experimental and theoretical study. Two fully alkylated co-catalysts (triethylaluminium, TEA, and triisobuthylaluminium, TIBA) and their combinations with two chlorinated ones, DEAC (diethylaluminiumchloride) and EADC (ethylaluminiumdichloride), were employed in ethylene/1-butene co-polymerization using a commercial TiCl4/MgCl2 catalyst. The highest co-polymerization rate was found for TEA and TIBA, without the addition of chlorinated co-catalysts. According to the high temperature gel permeation chromatography and the rheometric mechanical spectrometer analyses, the composition of DEAC with TEA and TIBA lead to the production of polymers with the highest molar mass and longer relaxation times. The promising influence of chlorinated Al-alkyl co-catalysts was on the comonomer incorporation since the combination of TIBA + DEAC could promote it up to 34%. Eventually, to elucidate the role of the co-catalysts on the comonomer response, density functional calculations were performed using ethylene and propylene as monomers. Lower energy barrier was observed in propylene insertions in the presence of DEAC and TIBA co-catalysts, demonstrating their positive impact on comonomer response, in comparison to TEA and EADC, which confirm the experimental evidence.

A review on microphase separation measurement techniques for polyurethanes

Polyurethanes (PUs) microstructure and characteristics is strongly affected by microphase separation that arises from the thermodynamic immiscibility between the hard and soft segments. The extent of phase separation as well as the morphology and size of the separated phase governs their mechanical, electrical, thermal, and functional properties. This review: (1) provides an insight into how phase separation affects PU properties, (2) explains methods used to study PU phase separation. We review approaches from the simplest one, that is, the transparency measurement, to the more advanced methods including the spectroscopic techniques (infrared, nuclear magnetic resonance spectroscopies and X-ray scattering), rheological instruments ( rheometrics mechanical spectrometer), and thermal analyses (differential scanning calorimetry). We also discuss the theoretical calculations and the molecular modeling used to study PU phase separation.

Viscoelastic behavior of silicone/clay nanocomposite coatings

Rubber/clay nanocomposites (RCNs) have attracted an emerging interest from academia and industry alike due to their outstanding tunable properties. The present paper addresses the viscoelastic behavior of silicone/clay systems in order to get an understanding of physical interactions in the RCNs systems as well as making possible interpretation of the effect of nanoparticle shape and surface functionality on viscoelastic behavior of molten RCNs. Rheological behavior determination of silicone/clay composites provides insight into dependency of properties of resulting nanocomposite coatings on processing and preparation conditions. The effect of bare and (3-aminopropyl) triethoxysilane (APTES) functionalized platy and tubular clays on viscoelastic behavior of silicone rubber nanocomposites were investigated by rheometric mechanical spectrometer (RMS). The analysis was set to the strain and frequency sweep tests, where the linear viscoelastic zone of the uncured nanocomposites were determined by dynamic strain sweep and then frequency sweep to probe into the role of dispersion of nanoparticles in silicone matrix. Well-known Han, Cole-Cole and van Gurp-Palmen models were applied to peruse silicone/clay interaction and to find additional information on rheological properties of nanocomposites under the influence of the shape, surface chemistry and content of nanoparticles. The findings depicted the effective role of physical interactions on APTES-functionalized clay on appropriate dispersion of clays throughout silicone matrix. This effect was more obvious in the presence of platelet-like clays in view of improved intercalation and/or exfoliation.

Micro powder poly lactic acid/carbon black composite as a bio printing ink

Bio toners represent a novel class of electrostatic imaging powders which provide sustainability, compostability and bio-degradability. Due to the advantages of bio toners, this paper focused on the preparation of a bio-based micro powdered composite derived from poly lactic acid and carbon black to apply it as an electrophotographic printing bio ink. The bio toner was characterized by particle size analyzer, differential scanning calorimetry, scanning electron microscopy, Fourier-transform infrared spectroscopy and thermogravimetric analysis. The viscoelastic properties were calculated with rheometrics mechanical spectrometer. These properties were then used to estimate the strain deformation of the toner as it passes through the nip with arbitrary residence time and nip pressure as a function of gel content. The outcomes of this study proved that the poly lactic acid is an appropriate polymer for the production of toners in terms of processing, printing efficiency. The bio toners' results demonstrated the promising and worthy outcomes in comparison to commercially available petroleum-based toners.

Evaluation of non-Einstein rheology behavior of soft nanoparticles/epoxy nano-composites and their multifunctional effects on curing kinetics

Non-Einstein rheology behavior is developed by using Polystyrene soft nanoparticles (PS-SNPs) in order to reduce viscosity and therefore the flow-ability of nano-composite during molding. PS-SNPs are synthetized by intramolecular crosslinking where the synthetized PS-SNPs’ diameter is kept smaller than the diameter of epoxy chains to result the viscosity reduction through non-Einstein like behavior which is confirmed by DLS measurements. Also rheometric mechanical spectrometer (RMS) test showed about 50% viscosity reduction and the thermodynamic analysis showed that no phase separation will occur during curing process which is usual in epoxy/PS nano-composites. Also the effect of SNPs on epoxy crosslinking kinetic is studied by implementing non-isothermal differential scanning calorimetry (DSC). Using model-free approach to investigate the kinetic itself and its parameters, we have found that the activation energy is lowered by adding SNPs. Also as more conversion took place, the reduction of pre-exponential factor (showing the collision of reacting groups) occurred due to the linear growth of epoxy at early stages of the conversion and network growth is triggered at more conversions. These phenomena propose that for non-Einstein like behavior the polymer matrix molecular weight should be either more than critical molecular weight of entanglement or comparable with molecular weight among entanglements.

In-situ microfibrillar PP–PA6 composites: rheological, morphological and mechanical properties

In this study, the rheology, morphology and mechanical properties of microfibrillar composites based on polypropylene reinforced with polyamide 6 (PA6) fibres have been investigated. Influence of different factors such as the PA6 composition and drawing ratio on the output of the extruder, and the compatibilizer composition on the properties of these composites, were investigated. The results of rheometric mechanical spectrometer rheological measurements and melt flow index (MFI) showed that the storage modulus, loss modulus and complex viscosity of the microfibrillar composites are directly related to the composition of PA6. It was also shown that the presence of compatibilizer was the main factor that led to decrease of some properties including the storage modulus, loss modulus and complex viscosity and increase in the MFI. The results of mechanical tests on samples prepared with different drawing ratios showed that by increasing the drawing ratio from 3 to 5, the mechanical properties increase, while increasing draw ratio from 5 to 8 reduces the mechanical properties. With the increase in the composition of the polyamide phase, the tensile strength of microfibrillar composite compatible with polypropylene-grafted-maleic anhydride initially increased; however, the tensile strength decreased with a high composition of polyamide phase. Scanning electron microscope images also revealed that the presence of the compatibilizer in the microfibrillar composites leads to decrease in the number of undeformed drops, while it reduces the micro-fibres diameter, which greatly improved the final properties of the composites.

Edge protection improvement of automotive electrocoatings in the presence of silica nanoparticles

The present study develops a method for edge coverage improvement of the cathodic electrocoatings by silica nanoparticles. The effect of silica nanoparticles on the rheology of curing process, anti-corrosion performance, edge protection, and morphology are studied. Field emission scanning electron microscopy (FE-SEM) is utilized to investigate the dispersion of nanoparticles in the coating matrix. The anti-corrosion performance is studied by electrochemical impedance spectroscopy (EIS) and salt spray tests. Rheometric mechanical spectrometer (RMS) and dynamic mechanical thermal analysis (DMTA) are used to investigate the rheology of the curing process and curing behavior of the coatings respectively. Minimum melt viscosity has increased significantly in the presence of the 4wt% nanoparticles. Results show significant improvement of edge coverage in presence of the 4wt% nanoparticles.

Improvement of the edge protection of an automotive electrocoating in presence of a prepared epoxy-amine microgel

Abstract The present study developed a method for modification of the cathodic electrocoatings formulation in order to improve their edge protection and anti-corrosion properties using epoxy-amine based microgels. An epoxy-amine microgel was prepared by reacting an epoxy resin, with methyl ethanolamine and diketimine. The prepared microgel had a mean particle size of 120 nm. Various contents of the microgel (2–8 wt%) were incorporated into an automotive electrocoatinging bath. The pigment to binder ratio was kept constant (1:6) for all samples except for the HPBR (high pigment to binder ratio sample, 1:4). The effect of the microgel on the rheology of the coatings was investigated by rheometric mechanical spectrometer (RMS). Minimum melt viscosity has increased significantly in presence of 4 wt% of microgel particles. The micrograph images obtained from field emission scanning electron microscopy (FE-SEM) indicated that the prepared epoxy-amine microgel, had a microsphere shape. Dynamic mechanical thermal analysis (DMTA) was used to study the effect of microgel particles on the curing behavior and the cross-linking density of the coatings. Pull-off test was used to investigate the microgel effect on adhesion strengths of the electrocoating. Glossmeter and profilometer were used to analyze surface morphology. Microgel particles did not significantly change gloss and roughness of the electrocoatings. Electrochemical impedance spectroscopy (EIS) and salt spray testing confirmed that in presence of 4 wt% of microgel, the anti-corrosion properties and edge protection were improved significantly.

Relationship between dye sorption and morphology in polypropylene/poly (butylene terephthalate) microfibrillar blend nanocomposite fibers

In this research work, the relation between microstructural enhancement and dyeing behavior of immiscible blend nanocomposite fibers was investigated using scanning electron microscopy, transmission electron microscopy, X-ray diffraction patterns, and rheometric mechanical spectrometer along with quantitative analysis of dye sorption. A novel microfibrillar morphology blend fiber, in which poly (butylene terephthalate) nanocomposite fibrils uniformly distributed in the cross section of polypropylene matrix, was successfully developed using melt compounding process. Preferred location of nanoclay had improving effect on poly (butylene terephthalate) fibril formation such that there was an organoclay concentration above that fiber with fine microfibrillar morphology could hardly be produced. It was demonstrated that nanoclay melt intercalation and partitioning controlled the activation energy of dyeing. The maximum sorption rate was achieved by utilizing compatibilizer to transfer part of nanoclay platelets into the polypropylene matrix.

Polylactide/Polyethylene/Organoclay Blend Nanocomposites: Structure, Mechanical and Thermal Properties

Structure and physical properties of PLA/PE/organoclay with and without compatibilizer (PE-g-MA) with PLA as a matrix phase were investigated by X-ray diffraction, transmission electron microscopy, rheometric mechanical spectrometer, thermal gravimetric analysis, dynamic mechanical thermal analysis and Mechanical experiments. Two types of compatibilized-blend nanocomposites were prepared by two feeding orders: (1) simultaneous feeding, (2) PLA/organoclay-based master batch. The XRD results showed an intercalated structure for nanocomposites. The mechanical results demonstrated that presence of PE and compatibilizer improved the elongation at break, while organoclay enhanced Young's modulus. Thermogravimetric analysis showed that organoclays could retard the thermal decomposition process in the nanocomposites.

CRYSTALLINE STRUCTURES AND α → β AND γ POLYMORPHS TRANSFORMATION INDUCED BY NANOCLAY IN PVDF-BASED NANOCOMPOSITE

Poly(vinylidene fluoride) (PVDF) nanocomposites were prepared by melt-mixing. The dispersion of clay platelets and rheology of nanocomposites were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and rheometric mechanical spectrometer (RMS). The transformation of α to β and γ phase in PVDF was induced by the addition of nanoclay and subsequently the isothermal crystallization kinetics of neat PVDF and its nanocomposite have been investigated. The interaction between clay nanofillers and PVDF macromolecular chains induced the change of conformation from trans-gauche to all-trans crystal structure in PVDF segment. The isothermal crystallization of PVDF/clay nanocomposites was carried out by Differential Scanning Calorimetry (DSC) technique. The influence of clay platelets on nucleation crystallization rate and Avrami exponent were studied. PVDF/clay nanocomposite showed higher crystallization rate indicating that nanoclay has acted as an effective nucleation agent. This nucleation effect of nanoclay increased the Avrami exponent and decreased the degree of crystallinity.

Morphological studies of (polyamide‐6)/(silane‐grafted high‐density polyethylene)/nanoclay ternary nanocomposites

In this work, the influence of organoclay incorporation along with silane grafting of high‐density polyethylene (HDPE) on compatibilization and morphology of HDPE/(polyamide‐6) (PA6) blends was investigated. Analysis by Fourier‐transform infrared spectroscopy was done for the investigation of grafting efficiency of specimens. Scanning electron microscopy and thermal properties (diffraction scanning colorimetry) were examined to study the effect of silane grafting as well as adding organoclay in compatibilizing blends. Small‐angle X‐ray scattering, transmission electron microscopy, and dynamic rheology (Rheometric Mechanical Spectrometer) were also used to explain morphological changes. The results of scanning electron microscopy indicated that silane‐grafted HDPE had hydrophilic characteristics and therefore was more compatible with PA6 than neat polyethylene. Furthermore, in the same way, adding nanoclay to this blend resulted in more uniform and finer morphology. Results of diffraction scanning colorimetry confirmed the compatibilizing effect of both silane grafting of polyethylene and use of organoclay in blends by showing a strong deviation of separate melting peak of PA6 in the composites to reduced intensity and shift to lower temperatures. J. VINYL ADDIT. TECHNOL., 21:191–196, 2015. © 2014 Society of Plastics Engineers

Evaluation of flow-induced nanoclay orientation and microstructural stability in polyethylene/clay nanocomposites via melt rheological and thermal analysis

AbstractThe effects of shear rate upon the flow-induced nanoclay orientation and morphological stability in film blown polyethylene clay nanocomposites were studied by means of linear and nonlinear rheological characterization parallel with differential scanning calorimetry and X-ray diffraction (XRD) analyses. Nanocomposite samples were prepared using a modular twin screw extruder followed by film processing technique. XRD analysis performed on film samples showed that the samples exhibited intercalated/exfoliated microstructure. The 3D physical networks were formed by the clay nanolayers in the structures of undrawn samples. However, the breakdown of the clay physical networks during film processing as a result of the imposed shear field within the die area and also an elongational flow field was evidenced. Time sweep test performed at various shear rates and shearing times using a rheometric mechanical spectrometer showed that, in all samples, the time required for the restructurization of the clay nanolayers during relaxation of the melt was found to be higher than 3600 s.

Studying the rheology, optical clarity and surface tension of an acrylic/melamine automotive clearcoat loaded with different additives

Acrylic/melamine based automotive clearcoats were prepared by inclusion of functional and conventional additives. The conventional additives used were based on polysiloxane chains without any reactive groups. On the other hand, the functional additives were based on polyacrylate and polysiloxane backbones. The additives were added to the clearcoat formulations at different concentrations. Surface tension, optical properties and rheological behaviors of the clearcoats were studied by tensiometer, gonio-spectrophotometer, rheometric mechanical spectrometer (RMS) and Brookfield techniques. Results showed that addition of both conventional and functional additives reduced the surface tension of the clearcoat up to a certain value of the additive concentration. It was seen that functional additives could reduce surface tension much greater than the conventional ones. The coating clarity and transparency were not affected in presence of conventional additives. However, the functional additives, especially the one having higher molecular weight, reduced the coating transparency. The clearcoat viscosity was increased using functional additives. A shear thickening behavior of the clearcoats loaded with functional additives was seen. The conventional additives did not change the clearcoat viscosity. It was concluded that the additive functionality, molecular weight and chemical structure were influential parameters affecting the final properties.

Effect of the melt viscoelastic behavior of components on the morphology development of polymer blends in a twin‐screw extruder

AbstractThe aim of this work was to study the role of effective parameters in the morphology evolution of polymer blends in a twin‐screw extruder with an emphasis on the effects of the melt viscoelastic properties of the blend components, screw speed, and flow field changes along the extruder. Two sets of blend samples based on polypropylene/polyamide 6 with the same composition (90/10) and polypropylene matrix but with two polyamide 6 grades differing in their viscoelastic properties were considered. The effect of the compatibilizer (maleic anhydride grafted polypropylene) was also investigated. The morphology of the blend samples were studied with scanning electron microscopy, and the melt linear viscoelastic properties of the samples were measured with a rheometric mechanical spectrometer. The melt‐blending processes were carried out in a modular twin‐screw extruder. The trend of the polyamide dispersed particle size changing with increasing screw speed was found to be different for the two types of blends. Considering of the role of the compatibilizer in coalescence, this could mainly be attributed to the different melt viscoelastic properties of the blend constituents. Similar explanations were given for the morphological changes that occurred along the screw. It was demonstrated that the viscosity ratio of the blend components is not necessarily the only material‐dependent parameter that affects the dispersed particle size: the viscoelastic properties (particularly the flow‐induced elasticity ratio) of the blend components can also play a significant role in determining the particle size distribution. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Parameters affecting the grafting reaction and side reactions involved in the free‐radical melt grafting of maleic anhydride onto high‐density polyethylene

AbstractThe parameters affecting the grafting reaction and side reactions in free‐radical melt grafting of maleic anhydride (MA) onto high‐density polyethylene with the aid of 2,5‐dimethyl‐2,5‐di(t‐butyl peroxy)hexane peroxide(DTBPH) have been studied using an internal mixer. MA grafting degree of the maleated samples was measured with titrometry and FTIR spectroscopy methods. The extent of chain‐branching/crosslinking side reactions was evaluated with gel content and MFI determination. The flow behavior and melt viscoelastic properties of the samples were measured using a rheometric mechanical spectrometer. DTBPH and MA concentrations, reaction temperature, rotor speed, the type and concentration of coagents were among the studied parameters. The results show that MA and DTBPH concentration has a major role on the grafting reaction, chain‐branching/crosslinking side reactions and also the grafts microstructure in the final product. The reaction temperature has a complex effect on the maleation reaction. Increasing the rotor speed causes an increase in MA grafting degree of the samples and reduces the competitive side reactions. By using Gaylord additives, gel formation reduces at the expense of a dramatic decrease in the grafting degree. MA grafting degree is increased by the use of comonomers in the reaction and this is accompanied with a decrease in crosslinking side reaction when the vinyl type styrene comonomer is used. The results of processing torque in combination with the measurements of the melt viscoelastic property and gel content of the samples provide a great insight into understanding the gel formation mechanism. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

Preparation and Characterization of HMW PA 6 via Anionic Polymerization of ∊-Caprolactam by Using a Mixture of Di- and Tri-functional Chain Initiators

Abstract In the present work, an attempt was made to synthesis polyamide 6 through anionic polymerization of e-Caprolactam by using a mixture of Diphenylmethan 4, 4-di and tri-isocyanate as a chain initiator and sodium caprolactamate as a catalyst. Polymerization was carried out in a laboratory internal mixer (Brabender). The rotor speed, reaction temperature and reaction time were among the processing variables studied. The prepared samples were characterized by Thermogravimetry Analysis (TGA), Differential Scanning Calorimeter (DSC) and FT-IR spectroscopy. The flow behavior and melt viscoelastic properties of the samples were studied by using a Rheometric Mechanical Spectrometer (RMS). The polymerization reaction was found to be very fast and was completed within 6 minutes. This was detected by following the mixing torque which reached to a steady state after passing through a maximum. The pronounced decrease in the torque was found to be determine by the thermomechanical degradation as a predominating mechanism. The polyamide 6 prepared in this work showed greater melt elasticity, much higher molecular weight and slightly narrower molecular weight distribution in comparison with the commercial grades of polyamide 6. The crystallinity of the samples was also higher than that of the commercial polyamide 6. These results were explained in terms of contribution of fraction of the molecules possessing single long chain branch formed as a result of three functional nature of the chain initiator. Increasing the rotor speed was found to have strong influence on lowering molecular weight as well as narrowing the molecular weight distribution through increasing the extent of thermomechanical degradation. Increasing the initial set temperature in the studied range had no appreciable effect on polymerization rate and degree of conversion. It was demonstrated that the results of melt viscoelastic measurements performed on the samples collected at different polymerization times can provide valuable information to follow the polymerization reaction.